1. Field of the Invention
The invention relates to the field of medical devices. More particularly, the invention relates to ultrasound endocavitary imaging devices.
2. Background Information
Various ultrasound techniques and devices have been developed for imaging the interior of a body (hereinafter, "body" refers to various types of subjects, such as humans, animals, non-living structures, etc.). One application of ultrasound imaging has been in the medical field, and in particular, in endocavitary probes (e.g., biopsy guidance endocavitary probes). Such probes may be used, for example, for endovaginal examination (e.g., to examine the uterus, ovaries, etc.), endorectal examination (e.g., to examine the rectal wall, prostate, etc.), and/or other medically-related applications. Typically, endocavitary probes include a linear array transducer positioned at the distal end of the probe that is to be inserted into a cavity of a body. The transducer provides an imaging plane for viewing structures/features of the body and/or another instrument (e.g., a biopsy needle) that, for example, may be guided into the body via the probe. The imaging plane may be provided at a side of a probe (corresponding to a "side-fire" transducer) or the front of the probe (corresponding to an "end-fire" transducer).
Since such linear array transducer endocavitary probes provide one imaging plane at any time for viewing the interior of the body and/or another instrument (e.g., a biopsy needle) that may be guided into the body via the probe, the ultrasound images provided by such probes are generally limited to a single plane. Unfortunately, such 2D (two-dimensional) images typically do not provide desired accuracy of structures/features within a body. In applications where a relatively high level of imaging accuracy may be critical, such as biopsy needle guidance through or in proximity to sensitive bodily structures which may need to be avoided by the needle, such linear array transducer probes may not be practical.
Several techniques for improving the above-mentioned limitation(s) of single linear array transducer endocavitary probes have been proposed, but each is relatively limited as well. For example, some endocavitary probes utilize a mechanical, rather than a linear array, transducer. Such mechanical transducer probes provide a single imaging plane at any one time, but the mechanical transducer may be rotated up to 180 degrees or even more to provide multiplane three-dimensional (3D) orientation in a field of view. However, end-fire multiplane single mechanical transducer probes cannot be used for biopsy guidance, since the biopsy needle is only visible in at most one plane of the rotation. Moreover, side-fire multiplane single mechanical transducer probes are unable to provide viewing of a forward-penetrating biopsy need at all.
In addition to the single-plane linear array transducer probes and the multiplane mechanical transducer probes described above, some biplane probes have been proposed. One type of a biplane probe utilizes a dual convex oblique end-fire linear array transducer structure, which generates two intersecting orthogonal imaging planes to provide 3D orientation in the field of view. However, this type of biplane probe is limited to only one imaging plane, since the two imaging planes intersect over one transducer, not along the biopsy needle. A second type of a biplane probe utilizes a convex and flat side-fire linear array transducer structure, which generates two non-intersecting orthogonal imaging planes to provide an indication of 3D orientation. However, this second type of a biplane endocavitary probe does not allow viewing of a biopsy needle in either imaging plane.
Thus, what is desired is an ultrasound endocavitary probe that provides simultaneous viewing of an instrument, such as a biopsy needle or other instrument, in two imaging planes.